want to bring in elizabeth cohen. i love stories like this. it's like wow. >> amazing. >> to see that guy smile and say i'm hopeful when he looks at the other arm, maybe this other arm will work well. how did they do this? >> get to one why arm is doing better than the other arm. it may have to do with where the transplants took place. on the right one it was actually above, so the new arm is -- it was here, it was from here down. the other one from somewhere around here down. the more arm you have to transplant the more difficult time somebody's going to have. so that's an important thing to remember. so the more arm you have to transplant, the more difficult the recovery's going to be because these doctors are putting together tendons, muscles, nerves, blood vessels. really tiny surgery. they practiced on cadavers first which i thought was fascinating. trained surgeons, they practiced on cadavers first. >> is it possible that -- he's hopeful, the second arm, is it possible he will have full functioning arms at some point? >> he may not have